Allright, dumb questions. I have a red in my secondary using up my airlock. I never even gave it any thought, and thus started to brew up a batch of wheat for the primary. Problem is, I should have ordered a 2nd airlock, because I only have the one.

Can I use plastic wrap and a rubber band on the secondary (carboy) and steal that airlock for my primary, or is there a better short term answer?

What are you using for a primary? Bucket or carboy? If it is a bucket get some tubing (not sure of the diameter as I have not used a bucket) that fits in the hole in the lid. If it is a carboy use a 1" ID piece of tubing, it will fit snugly in the mouth of the carboy. In either case put the other end of the tube in a large jar with sanitizer in it.

Also, I was talking to an old school homebrewer at work the other day. He was saying they used small diameter tubes and sealing wax to create an airlock. I would simply add that to your tube as a way to positively seal it.